Bearing and process of forming the same



June 2, 194 w. E. M CULLOUGH ETAL 2,284,670

BEARING AND PROCESS OF FQRMING THE SAME Filed Feb. 2, 1940 FIG.7.

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INVENTORS WILLIAM E.McGULLOUGH BY EDWIN O.GOERKE W AfRNEYg Patented June2, 1942 BEARING AND PROCESS OF FORMING THE SAME William E. McCullough,Detroit, and Edwin 0. Goerke, Dearborn, Mich., assignors to BohnAluminum & Brass Corporation, Detroit, Mich., a corporation of MichiganApplication February 2, 1940, Serial No. 317,028

11 Claims.

The invention relates to bearings formed of alloys, chiefly of aluminumto which one or more other metals, such for instance as tin, are addedto improve the bearing qualities. Heretofore, bearings have been formedof an alloy of aluminum containing from to of tin. Such bearings havebeen first cast and then machined to size. The machining operation isexpensive, while the large amount of material removed further increasesthe cost of manufacture.

It is the primary object of the instant invention to reduce the cost ofmanufacture of bearings from such alloys, and further to obtain aproduct which has improved characteristics. To this end, the inventionconsists in the process and product as hereinafter set forth.

In the drawing:

Figure 1 is a diagrammatic representation of our improved extrusionprocess;

Figure 2 illustrates the manner of skiving or finishing the surfaces ofthe extruded member;

Figures 3 to 8 illustrate various cross sectional shapes of the extrudedmember.

Our improved process consists essentially in a novel method of extrudingthe metal particularly adapted to aluminum alloys containing from 5% to15% of tin. The member thus extruded is of a cross sectional thicknesssubstantially that of the fin shed bearing, so that it is only necessaryto remove the oxide film from the surfaces thereof. The extruded memberis then subjected to further operations for forming the completedbearing.

Extrusion method Pure aluminum and certain of its alloys can befashioned into various cross sectional shapes by extrusion processesheretofore used. We have found, however, that an aluminum alloycontaining from 5% to 15% of tin cannot be successfully extruded in suchmanner. This is primarily for the reason that there is a pronouncedtendency for the tin component to sweat or be forced out of the alloy.Thus, if a billet of the alloy is heated to the usual temperature forextrusion, such as 800 F., and is placed in a container only slightlyless in temperature in accordance with the general practice, theextruded product will not be satisfactory. We have, however, discoveredthat if the temperature of the billet and that of the container isconsiderably reduced, the extruded bar, preferably cooled by water. willhav desirable characteristics. As a specific example, we have found thata billet of the composition: aluminum, 89%; copper, 2%; magnesium, 1%,and

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tin, 8%, if heated to a temperature from 250 F, to 350 F. and placed ina container heated from 550 F. to 600 F. can be extruded without thesweating out of the tin constituent, and will .produce a bar havinghighly desirab e characteristics.

It will be appreciated that since the melting point of tin is 450 F.,the unique feature of our invention lies in keeping the billettemperature below this point, and keeping the container and dietemperature slightly above the same. Thus, the pressure to which thebillet is subjected will not cause the expulsion of the tin contenttherefrom as would be the case if the temperature of the billet wereabove the melting point of tin. On the other hand, the temperature ofthe con tainer and the die being above the melting point of tin, alubricating film of molten tin will be formed on the surface of thealloy which will reduce friction and facilitate extrusion.

As diagrammatically illustrated in Figure 1 of the drawing, A is thecontainer which is maintained by suitable means (not shown) at atemperature from 550 F. to 600 F. B is the billet of alloy within thecontainer, C is the compression plunger and D the die through which themetal is extruded. It is usual with apparatus heretofore used for theextrusion of aluminum to form the die at its entrance end with rightangle or shearing edges. We have found, however, that with suchconstruction when used with aluminum alloys having from 5% to 15% oftin, there is a tendency to tear and crack the edges and surfaces of themetal, but such difliculty we have avoided by forming the die with acurved surface at the entrance end, as indicated at E, Figure 1.

The extruded member may be varied in cross sectional contour accordingto the particular bearing which is to be formed or the subsequent stepsemployed in the completion of the bearing. Thus, in Figures 3, 4 and 5the extruded member is in the form of a flat bar but with its edgeportions of different shape. Figure 6 shows a bar having angle flangesor rib at the opposite ends thereof. Figure 7 shows a member ofsemi-cylindrical or segmental cross section, and Figure 8 shows a fullcylindrical cross section. The extruded member which may be from fifteenfeet to thirty feet in length is next drawn through a skiving die F tofurther accurately size the section and to remove the oxide film fromthe interior and exterior bearing surfaces. In case of the fullcylindrical cross section this operation may be performed by internaland external breaching. The extruded member is next passed through aprogressive die (not shown) in which it is submitted to the followingconsecutive operations:

(1) Cutting to prop'er length for a given bearmg;

(2) Cold coined to perfect half-circular cross section and with a radiusor a longitudinal curve at each end;

(3) Perforated with oil holes;

(4) Stamped with oil grooves, as desired.

If the extruded member is in the form of a flat bar this must be bentlongitudinally into arcuate form. If the extruded member is of arouateor full cylindrical cross section, then it is merely severed intobearing lengths.

We have found that extruded bars as above described, are capable ofwithstanding such subsequent cold operations, whereas cast material ofthe same composition is not susceptible to this amount of cold workingwithout checking or cracking. Such difference we attribute tocharacteristics imparted to the material by the extrusion process.

What we claim as our invention is:

1. In a process of forming bearings from aluminum alloys containing from5% to 15% of tin, the steps of extruding a. billet formed of suchmaterial preheated to a temperature from 250 F. to 350 F. and from acontainer at a temperature from 550 F. to 600 F. to form a member ofpredetermined cross sectional contour of substantially finisheddimensions and subjecting said member to further operations forfashioning the same to finished form.

2. In a process of forming bearings from aluminum alloys containing from5% to 15% of tin,-

the steps of extruding a billet formed of such material preheated to atemperature from 250 F. to 350 F. and from a container at a temperaturefrom 550 F. to 600 F. to form a member of predetermined cross sectionalcontour of substantially finished dimensions, passing said memberthrough a skiving die to accurately size the section and remove oxidefilm from the bearing surfaces thereof, cutting to predeterminedlengths, and cold coining to finished size and form.

3. In a process of forming bearings'from aluminum alloys containing from5% to 15% of tin, the steps of extruding a billet formed of suchmaterial preheated to a temperature of from 250 F. to 350 F. and from acontainer at a temperature from 550 F. to 600 F. to form a bar ofapproximately the cross sectional contour and dimensions of the finishedbearing, passing said bar through a skiving die to accurately size thesection and remove oxide film from the bearing surfaces thereof, cuttingto bearing lengths, and cold coining to finished size and form.

4. A segmental bearing formed of extruded aluminum alloy containing from5% to 15% of tin.

5. A segmental bearing formed of extruded aluminum alloy containing:tin, 8% copper, 2% and magnesium, 1%

6. In a process of forming bearings from aluminum alloys containing from5% to 15% of tin, the steps of preheating a billet of the said alloy toa temperature less than the melting point of the tin constituent, andextruding the billet at such temperature.

7. In a process of forming bearings from aluminum alloys containing from5% to 15% of tin, the steps of heating the container and die of anextrusion apparatus to a temperature higher than the melting point oftin, preheating a billet formed of the said alloy to a temperature lessthan the melting point of the tin constituent, and extruding the billetfrom the container through the die at the said temperatures.

8. In a process of forming bearings from aluminum alloys containing from5% to 15% of tin, the steps of heating the container and die of anextrusion apparatus to a temperature notless than 550 F., preheating abillet of the said alloy to a temperature of not over 350 F., andextruding the billet from the container through the die at the saidtemperatures.

9. In a process of forming bearings from aluminum alloys containing from5% to 15% of tin, the steps of heating a container and die of anextrusion apparatus to, a temperature from 550 to 600 F., preheating abillet of the said alloy to a temperature from 250 F. to 350 F., andextruding the billet from the container through the die at the saidtemperatures.

10. A bearing formed of extruded aluminum alloy containing from 5% to15% of tin.

11. A bearing formed of extruded aluminum alloy containing: tin, 8%;copper, 2%; and magnesium, 1%.

WILLIAM E. MCCULLOUGH. EDWIN O, GOERKE.

